According the Youtube poster: Bélisaire au "Liberty Theater" de Eunice, Louisiane.
There's a French band called by that name, might be them. The accordion player looks a bit younger here than the one i met at the jams in Saulieu, and the fiddle player looks as the same feller too .... Marc maybe knows if it's the same band? They played at the Raamsdonksveer Festival last year, good show ... http://groupebelisaire.free.fr/